The explosion occurred before 1:00 p.m. at a SMECO power facility in Southern Maryland, authorities confirmed to the Associated Press. The incident is not believed to be terror related.

Buildings including the White House, State Department, Capitol and Justice Department lost power for more than an hour but have gradually begun coming on line, according to reports.

A PEPCO outage map showed multiple locations around Washington, D.C., plunged into darkness as of 1:30 p.m. Less than 1,000 customers remained without power by about 2:00 p.m., but some of them are not estimated to have their services restored until Wednesday evening.

The State Department's daily news briefing was suspended after power was lost.